Resnatron filament basket



W. H. KOHL RESNATRON FILAMENT BASKET Nov. 11, 1952 5 Sheets-Sheet 1 Original Filed Nov. 19, 1949 INVENTOR. WALTER H. KaHL Nov. 11, 1952 w. H. KOHL RESNATRON FILAMENT BASKET Original Filed Nov. 19, 1949 3 Sheets-Sheet 2 INVENTOR. WALTER mu BY 2 7: g

Nov. 11, 1952 w. H. KOHL 2,617,960

RESNATRON FILAMENT BASKET Original Filed Nov. 19, 1949v E s Sheets-Sheet z H INVENTOR.

WALTER H. KOHL Patented Nov. 11, 1952 RESNATRON FILAMENT BASKET Walter H. Kohl, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, a

corporation of Iowa Original application November 19, 1949, Serial No. 128,380. Divided and this application October 20, 1950, Serial No. 191,224

4 Claims.

This invention teaches a method of making resnatron filament baskets.

This is a divisional application of my application entitled Assembly for Resnatron Filament, Serial Number 128,380, filed on November 19, 1949.

During recent years there has been a general trend in the electronic art to use higher and higher frequencies. The resnatron tube has been devised as one device operable at high frequencies. It is essentially a beam tetrode in which a plurality of radial beams are eminated from an annular cathode. It is necessary to maintain accurate alignment of the respective elements of the tube and, in particular, to have the individual emitting sections of the cathode located accurately in angular and radial position. The resnatron cathode is called a filament basket. The basket comprises a plurality of staple-shaped filaments supported at both ends by rings. A voltage is applied across the rings during tube operation and the resultant current flow through the filaments heats them until thermionic emission of electrons occurs. To obtain symmetry of operation not only must great accuracy be maintained in spacing the filaments equidistant about the periphery of the rings, but also the distance of each filament to the major axis of the basket must be maintained substantially the same. Heretofore the filaments have been assembled by hand and. the assembly was a difiicult, tedious, and time-consuming task.

It is an object of this invention, therefore, to

provide a jig which may be used for producing resnatron filament baskets.

A further object is to provide a jig which quickly and very accurately produces resnatron filament baskets.

Still a further object is to provide a jig which will reduce the cost of assembling a resnatron filament basket.

A feature of this invention is found in the provision for a resnatron filament jig comprising a base member which receives an upwardly extending member therein. A ring of the basket is placed over the upwardly extending member and a ring of solder is placed on the ring of the basket. The ends of the filaments are next placed into receiving slots formed in the ring and a holding ring is received in mating engagement over the first ring. The other ends are likewise held in a pair of rings and filament engaging and spacing members are placed against the outer edges of the filaments. A clamping means is threadedly received on the upwardly extending member and a plurality of wedges hold the filament engaging members in place. The entire jig is heated in a furnace to melt the solder rings for bonding the holding rings of the filament together. The jig is removed from the furnace and cooled. Upon disassembly an accurately dimensioned resnatron filament basket is obtained.

Further objects, features, and advantages of this invention will become apparent from the description and claims when read in the light of the drawings, in which Fig. 1 is a perspective view of a resnatron filament basket;

Fig. 2 is a sectional view taken along the line 2-2 in Fig. 1; and

Fig. 3 is an exploded perspective view of the jig of this invention with the respective parts of the filament basket interspersed in their respective assembly positions.

Referring to Fig. 1 an assembled resnatron filament basket is shown and comprises a plurality of filament staples 0 with their ends fastened to holding means H and 12. Each staple is spaced equidistant about the periphery of the holding means II and i2 and the distance to the center or active portions l3 of the staples from the major axis M of the completed assembly is very accurately maintained in a manner which will be later explained.

Fig. 2 is a sectional view taken along line 2-2 in Fig. 1 and shows the component parts of the resnatron basket.

The holding means l2 which clamps the upper ends of the filaments comprises a pair of rings l6 and I1 which fit together in mating engagement. Both rings are formed with an aligned axial opening. The upper ring 16 has an extending annular portion 18. A small vertical opening I9 is formed in the top of ring [6 at a position ofiset from the larger axial opening and extends only partially through the ring. The lower ring I! is formed with an upwardly extending portion 2| which is received in mating engagement by the upper ring [6. The distance from the axis 14 to the outer surface 22 of the extending portion 2! is carefully machined to a predetermined dimension.

The upper ring [6 has a filament engaging portion 23 which is formed with a plurality of slots adapted to receive the ends 25 of the filament staples. The slots are spaced equidistant about the periphery of the engaging portion and when the filament ends 24 are clamped between the lower ring I? and the engaging portion 23, the staples are spaced equidistant about the holding means 12.

An annular notch 26 is formed in the lower 3 ring I! and is adapted to receive a ring of solder 21.

The ends 24 of the filaments are cut and then accurately finished to a predetermined length and are held in abutting engagement with the outer surface 22. Thus, the distance between the central portion I3 of the filament and the axis I4 is maintained constant for all the staples. This accuracy of construction maintains symmetry between the active portions I3 of the filaments and the surrounding grids and anode of the resnatron.

The bottom holding means II also comprises a pair of rings 28 and 29 which clamp the lower ends 3| of the filament staples. The lower ring 29 has a staple engaging portion '32 which is formed with a plurality of slots for receiving the ends 3| of the filaments therein. The ring 28 fits in mating engagement with ring 29 and a rin of solder 33 fits between the two in an annular roove formed in the ring 28, The bottom holdingameans l l is formed with 'an opening; 34- which isin axial alignment :with the opening in the upper holding means [-2 but which is substantially larger in diameter thanthe upper opening.

A shoulder 36 is formed in the ring ,2 9 =by counterboring the lower end pf-the opening 73A.

:The endsjsl; of thestaples It] are maintained in abutting engagement with a should r 37 formed on the ring 28 and the length of:the bottom ends 3| and the distance of-the shoulder 3! from the axis l4 are maintained at predetermined vdimensions.

A horizontal opening 38 is formed; in the lower ring '29 for-holding the lower holding means. II in axial zalignmentgwith the upper holding means l2. The manner in-which the opening38 accomplishes the alignment will be explained hereafter.

1t is-seen from, the above description that the assembly oftheresnatron filament basket involves the jo ining together of a relatively large number .;of .differentparts which must .be very accurately positioned. For example, oftentimes 24 filament staples-are assembl in on baske and--it;.is,-.easily understood that to align;su ch;a number of s aples. x all a pe i herall b comes :quite a task.

The jig shown in Fig, 3 has been devisedto facilitate the assembly of the parts of the basket whi h a h wn i r p rse :amma-themfi of the jig.

A :base member 39 of generally cylindrical shape .is formed with. a vtapered opening which extends: from a. large diameter at'the top-4| .to a smaller diameterrat the bottomAZ. An annular shoulder 43 is formed adjacent the-bottomed? for supporting a disc M of the upright supporting member. The member 36 hasan upward extending portion comprising the relatively thin shoulder 45, a longer-middle section 41-, and atop section. 48 of smaller diameter than the middle sectionll. A longitudinalslotdfi isformedin the outer-surfaces of'the upper sectionAS; and the middlesection ll.

The ring -2 9 is received over the-upwardextending portion '36 and the shoulder "SS-isengaged by the shoulder 55. The solder ring- 33-is received in the-notch and the ring-28 is received .in mating engagement with the ring 29. The lower endstl-of the filament are; placed in the slots fillbetween the rings 28 and -29 withtheendsin abutting engagement with the shoulder 31.

The ring H is received over the upright member 46 and engaged by the shoulder.52. The upper ends 24 of the filament staples are arranged about the surfaces 53;andthesolder. ring 21 is placed in the groove 26. The upper ring I6 is fitted over the lower ring I! and the fila ment ends are received in the slots 54.

A clamping ring 56 is received over the upright member 4'6 and clampedagainstthe .ring It by a nut 51 which is threadabl received bythe upright member.

The clamping ring 58 is formed with a radial opening 58 and a vertical opening 59. A key 6| fits through the opening 58 and is received in the slot 49 for preventing rotary motion of the clamping ring. A second key 62 extends through the opening 59 and into the opening IS in the ring 1 6. Thus rotary motion of the ring [6 is prevented.

Four arcuately-shaped filament engaging portions 63 are fitted about the active portions I3 of the filaments. Each filament engaging portion 63 is formed with equally spaced slots 64 for receiving the filaments therein. The edges of the slots are slightly tapered outwardly to allow the jigto be disassembled. Oneof thefilament engaging portions is formed witha horizontal opening 66 for receiving a key -67 which extends through the opening 38 in the ring 29 and into the slot 49. This key .prevents rotarymotion of the-ring29 and thus the upper-and lowerv holding means may be maintained in axial alignment.

The engaging portionsfifi fit within the confines of the base member .SBJand wedge members 68 are received between .the innertapered wall (it of the base member and, the outersurface H of theengaging portions.

The 'juncti'onsbetween adjacent wedge porti0nsfi8 are, placed soas to be out of radialalignment with the junctions,betweenadjacent engaging portions 63.

-When the jig has beencompletelyassembled itis placed into aheatingunit and raised to a temperature sufiicient ,to melt the. solder rings 27 and .33. The jig is then removed from the heating .unitand allowed to cool. The Wedges E58 are-next. removed and thenrthe engagingportions63. The nut,5lis unscrewedand the clamping ringii] removed.

Thefilamentbasket may then be lifted from h pri ht member. and t finishe vp f fii l c obtained.

It i thu seen ha this inv tio ro ide a method of making a resnatron filament'basket by the use of a novel jig.

Although the invention has .beendescribed with respect ,to preferred embodiments thereof it is not to be so limited because modifications and changes are withinthefullintended scope as defined by. the appended claims.

I claim:

1. A resnatron filament basket comprising, a first rin formed with an upwardly extending portion, said extending portion (being Iorn'ied with a plurality of slots perpendiculartothemajor axis .ofsaid first ring, a plurality of stapleshaped filamentsthelower endsof said filaments received within the slot formed insaid extending portionand said. ends extending radially toward thermajor axis of said first annularring, asecond ring received in mating, engagement with said first ring and clampingthe ,lower ends of .said filaments,v an end. engaging portion of said second ring enga ing the,lower inwardly pointing ends of saidfilaments toretain .them'in afixed spatial relationship with themajor aXisof .the first. and second rings, ,.first.. bonding. means holding the first andsecondringsand the.lower ends of the filaments inia fixed relationship a third ring in axial alignment with said first and second rings engaging the upper ends of said filaments, an end engaging portion of said third ring in abutting engagement with the upper ends of said filaments to retain them in a fixed spatial relationship with the major axis of said third ring, a fourth ring in mating engagement with said third ring and clamping the upper ends of said filaments, a downwardly extending portion of said fourth ring formed with a plurality of slots perpendicular to the major axis of said fourth ring for receiving the upper ends of said filaments therein, and second bonding means uniting the third and fourth rings and the upper ends of said filaments in a fixed relationship.

2. A resnatron filament basket comprising, a plurality of relatively high electrically resistant staple-shaped filaments having the end portions out to very accurate lengths, a first annular clamping means receiving the upper end portions of said filaments and holding them in a fixed spatial relationship about the periphery of said first clamping means, an end engaging portion on said first clamping means in abutting engagement with the upper ends of said filaments and holding them equidistant from the major axis of said clamping means, a second annular clamping means receiving the lower end portions of said filaments and holding them in a, fixed spatial relationship about the periphery of said second clamping means, and an end engaging portion on said second clamping means in abutting engagement with the lower ends of said filaments and holding them equidistant from the major axis of said clamping means.

3. A resnatron filament basket comprising, a first ring formed with an upwardly extending portion, a second ring formed with a recess for receiving said upward extending portion therein, a third ring formed with a downwardly extending portion, a fourth ring formed with a recess for receiving said third ring therein, and a plurality of U-shaped staples with one of their ends fastened between the first and second rings and the other ends fastened between the third and fourth rings, respectively.

4. Apparatus according to claim 3 wherein the first and second rings are formed with an accurately dimensioned filament end engaging portion and the third and fourth rings are formed with an accurately dimensioned filament end engaging portion.

WALTER H. KOHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,451,987 Sloan Oct. 19, 1948 2,452,786 ONeill Nov. 2, 1948 

